Adsorbent material and method of preparing an adsorbent material

ABSTRACT

The present invention relates to an adsorbent material for chromatography comprising a polymer immobilised onto a support, wherein the polymer backbone is attached to the support by one or more linkages which comprise one or more amide groups. It further relates to a method for preparing an adsorbent material for chromatography wherein a support is reacted with a polymer.

[0001] The present invention relates to an adsorbent material. It alsorelates to a method of preparing an adsorbent material, and the use ofthe adsorbent material in chromatographic separation methods.

BACKGROUND OF THE INVENTION

[0002] When using chromatography for separating individual chemicalcompounds present in a mixture, the choice of a stationary phase isimportant to get good resolution, i.e., good separation of thecompounds. There is a wide variety of stationary phases available, whichhave different affinities to different compounds. More specifically, itis usually the surface of the stationary phase that interacts with thecomponents of the mobile phase in a desired manner, i.e., the stationaryphase acts as an adsorbent material.

[0003] Silica, or other inorganic oxides, can be used as the basematerial for stationary phases in chromatography. In order tofunctionalise the support material, a specific organic compound may beattached to the surface by reaction with e.g. silanol groups on a silicasurface. By varying the compound to be bonded to the surface, variouschromatographic behaviours can be achieved. However, silica and otherinorganic oxides may start to dissolve at high pH, causing leakage ofinorganic material, usually referred to as inorganic leakage. To avoidinorganic leakage, it is important to cover as much of the supportsurface as possible. The support is suitably a porous material havingpores of various sizes. The main part of the surface area of the supportmaterial is the area within the pores. It is therefore important thatthis part can be coated with, e.g., a polymer, to avoid inorganicleakage and to give good resolution.

[0004] The chromatographic stability of an adsorbent material is also animportant factor. By chromatographic stability is herein meant theability of the adsorbent material to keep its selectivity and retentionover a period of use.

[0005] Polymers may also be attached to a support surface by firstattaching a monomer onto the support surface followed by furtherpolymerisation. H. Engelhardt et al., Chemically Modified Surfaces,Proc. Symp 4^(th), Elsevier, 1992, 225-241, discloses a method ofcoating a solid support where a vinylsilane is bonded to a silicasurface followed by co-polymerisation of acrylamide onto the vinyl groupof the covalently attached vinylsilane. However, this will give apredominantly tentacle-type coating where most polymer chains areattached in a single point, with each polymer chain extending from thesupport as a “tentacle”, giving a both chemically and mechanicallyunstable attachment. Generally, the chemical bond between a coating ande.g. silica is often unstable, especially at low pH, which may giveleakage of organic material, usually referred to as organic leakage.Also, when polymerising vinyl monomers onto a solid support, remainingmonomers may be present on the support surface giving chemicalinstability. Alternatively, a preformed polymer may be attached onto asupport surface in multiple points. WO 98/27418 A1 discloses a method ofcoating a silica support by first binding a coupling agent onto thesupport surface and thereafter binding a preformed polymer to thecoupling agent. The preformed polymer comprises a totally saturatedcarbon chain with leaving groups. It is a rather complicated methodrequiring several process steps. Kurganov et al, Journal ofChromatography 261 (1983) 223-233, discloses a method for bonding acopolymer of styrene and methylvinyldimethoxysilane onto a surface ofsilica. However, the reactivity of methylvinyldimethoxysilane is muchlower than for styrene, which will favour homopolymerisation of styrenegiving only few silane monomer parts in the copolymer, thereby effectingthe number of linkages to the silica in a disadvantageous way.Alternatively, a chloromethylated polystyrene is reacted withaminopropyltriethoxysilane and thereafter bonded to a surface of silica.However, the basic nitrogen in the amino group in the spacer between thepolymer backbone and the silica is not an inert group and may take partin unwanted reactions. U.S. Pat. No. 4,914,159 discloses a process forimmobilising copolymers of (meth)acrylamides onto a silica gel. A(meth)acrylamide monomer is copolymerised with a silylating agent suchas methacryloyloxypropyltrimethoxysilane.

[0006] There is a need of further improved adsorbent materials andimproved methods of coating solid supports for making adsorbentmaterials. It is therefore an object of the present invention to providean adsorbent material for chromatography which has high chromatographicstability, which gives excellent resolution of chemical compounds to beseparated from a mixture and which has a high degree of surface coverageof the solid support. There is a further object of the present inventionto provide a method for preparing an adsorbent material forchromatography, which comprises few steps, which gives an adsorbentmaterial with high degree of surface coverage of the solid support, andwhich enables flexibility in providing adsorbent materials withdifferent chromatographic behaviour.

THE INVENTION

[0007] According to the invention it has surprisingly been found that anadsorbent material for chromatography having chromatographic stability,having a high degree of surface coverage of a support, giving excellentresolution, and which can be tailor-made for a desired separationcharacteristic, can be provided. The adsorbent material forchromatography comprises a polymer immobilised onto a support, whereinthe polymer backbone is attached to the support by one or more linkageswhich comprise one or more amide groups.

[0008] The present invention further comprises a method of preparing anadsorbent material for chromatography comprising immobilising a polymeronto a support, wherein the support is reacted with the polymer, therebyforming one or more linkages between the polymer backbone and thesupport, each linkage comprises one or more amide groups. Furthermore,the present invention comprises a method of preparing an adsorbentmaterial for chromatography comprising providing a polymer from amonomer mixture comprising an amide group containing silane, reactingthe polymer with a support to form one or more linkages between thepolymer backbone and the support. In both methods of the invention, thepolymer is suitably added as a solution to a suspension of the support.The support is suitably filtered off, washed, and dried. A further acidtreatment step is also suitably performed, suitably followed by anend-capping step wherein an end-capping agent, for example,chloro-trimethylsilane, hexamethyldisilazane or(N,N-dimethylamino)-trimethylsilane, is added to the support.

[0009] The present invention further comprises the use of the adsorbentmaterial for chromatography in chromatographic separation methods. Italso comprises the use of an adsorbent material for chromatographyprepared according to any of the methods of the present invention, inchromatographic separation methods. Such chromatographic separationmethods can be, for example, HPLC, supercritical fluid chromatography(SFC), and simulating moving bed (SMB).

[0010] The present invention further comprises a method of separatingchemical compounds from a mixture comprising contacting the mixture withthe adsorbent material for chromatography according to the presentinvention.

[0011] The support material of the present invention is suitably amaterial whose surface comprises groups susceptible to reaction withgroups on the polymer. The support material can be either an organic oran inorganic material. Organic support materials include polymericsupport materials such as poly(styrene-divinyl benzene), polyacrylateresins and polyacrylamide resins. Organic support materials, such aspolymeric support materials, are suitably functionalised to comprisegroups, such as hydroxyl groups, halogen groups, amino groups, or vinylgroups, susceptible to reaction with the polymer to be immobilised ontothe support. Inorganic support materials include inorganic oxides.Suitably, the surface of inorganic support materials comprises hydroxylgroups or groups convertible to hydroxyl groups. Suitably, the supportis an inorganic support, preferably an inorganic oxide such as alumina,titania, zirconia, chromia, silica, boria, toria, beryllia,silica-alumina and combinations thereof. Most preferably, the support issilica. The support material can be a particulate material, or, in theform of a piece, a sheet, a rod or a capillary coating. Preferably, thesupport material is a particulate material, suitably having a volumeaverage particle size of from about 0.5 to about 500 μm, preferably fromabout 0.7 to about 200 μm, most preferably from about 1 to about 40 μm.The particles are preferably substantially spherical. The particulatematerial suitably comprises pores. The pore size, pore volume andspecific surface area of the particulate support material may varydepending on the type of support material used, the characteristics ofthe polymer to be linked to the support and the desired separationcharacteristics when in use. The pore size range may be different fordiffusion pores and perfusion pores (flow pores). For diffusion pores,the pore size is suitably from about 20 to about 4000 Å, preferably fromabout 50 to about 500 Å. For perfusion pores, the pore size is suitablyfrom about 1000 to about 80000 Å, preferably from about 5000 to about50000 Å. The pore volume is suitably from about 0.1 to about 4 ml/g,preferably from about 0.3 to about 2 ml/g, most preferably from about0.5 to about 1.5 ml/g. The specific surface area is suitably from about1 to about 1000 m²/g, preferably from about 25 to about 700 m²/g. mostpreferably from about 100 to about 500 m²/g.

[0012] The polymer of the present invention suitably comprises groupssusceptible to reaction with the support. Such groups can be, forexample, vinyl groups, alkoxy groups such as methoxy, ethoxy, propoxy,butoxy and isobutoxy, halogens such as chlorine, bromine, iodine, andfluorine, secondary amino groups such as dialkylamine, an imidazolgroup, a morpholine group, or an azide group. Suitably, the polymer is apreformed polymer, preferably a co-polymer. The polymer is suitablyprepared by polymerising a monomer mixture comprising at least one vinylmonomer m₁ of the general formula (I):

[0013] wherein A is a halogen, a vinyl group, or, a silane group,wherein x=1-30, R₁ is hydrogen or C₁-C₄ alkyl, and R₂ is hydrogen ormethyl. The monomer mixture suitably further comprises at least onevinyl monomer m₂ of the general formula (II):

[0014] wherein R₅ is hydrogen or methyl, and E is any of the groups:

R₇—O—,

[0015] wherein m=0 to 20, R₆ is hydrogen or C₁-C₄ alkyl, and R₇ is afunctional moiety selected to give the desired separationcharacteristics of the finished adsorbent material. By the desiredseparation characteristics, is herein meant that a certain resolutionbetween a specific chemical compound of interest and other compounds isachieved. By varying R₇, the affinity of the adsorbent material tocertain chemical compounds will be different. For example, propertiessuch as hydrophobic-, dipol-dipol-, π-π-, electrostatic-, and stericinteractions, or chiral discrimination can be varied. The functionalmoiety R₇ can be varied within wide limits and can be, for example,hydrogen, C₁-C₃₀ alkyl, C₁-C₃₀ hydroxyalkyl, phenyl, benzyl, carboxyl,C₁-C₃₀ alkylcarboxyl, phenylcarboxyl, nitrophenyl, chlorophenyl, C₁-C₃₀aminoalkyl, aminophenyl, —N(Me)₃ ⁺Cl^(−, and —N(Me)) ₂(CH₂)_(p)SO₃,wherein p=0-5. When R₇ is any of C₁-C₃₀ alkyl, C₁-C₃₀ hydroxyalkyl,C₁-C₃₀ alkylcarboxyl, and C₁-C₃₀ aminoalkyl, preferably C₁-C₁₀ alkyl,C₁-C₁₀ hydroxyalkyl, C₁-C₁₀ alkylcarboxyl, and C₁-C₁₀ aminoalkyl isused, most preferably C₁-C₅ alkyl, C₁-C₅ hydroxyalkyl, C₁-C₅alkylcarboxyl, and C₁-C₅ aminoalkyl. The monomer mixture suitablyfurther comprises at least one vinyl monomer m₃ of the general formula(III):

[0016] wherein n=1 to 20, R₈ is hydrogen or methyl, R₉ is C₁-C₄ alkyl,R₁₀ is C₁-C₄ alkyl, R₁₁ is hydrogen or methyl.

[0017] For a polymer to be immobilised onto an inorganic supportmaterial, m₁ is preferably a monomer comprising a silane group. Thesilane group is suitably of the general formula (IV):

(B)_(y)(D)_(3-y)Si—  (IV),

[0018] wherein B is C₁-C₄ alkyl, C₁-C₄ alkoxy, halogen, hydroxyl,hydrogen, —N(R₃)_(z)(R₄)_(2-z), an imidazol group, a morpholine group,or an azide group, D is C₁-C₄ alkyl, y=1-3, z=1-2, R₃ and R₄ are,independently from each other, hydrogen, C₁-C₂₀ alkyl, or aryl.Preferred monomers m₁ are (meth)acrylamido alkylalkoxysilanes such as(meth)acrylamidopropyl-trimethoxysilane,(meth)acrylamidopropyldimethoxymethylsilane,(meth)acrylamidopropyl-dimethoxyethylsilane,(meth)acrylamidopropyl-monomethoxydimethylsilane,(meth)acryl-amidopropylomonomethoxydiethylsilane(meth)acrylamidopropyltriethoxysilane,(meth)acrylamidopropyldiethoxymethylsilane,(meth)acrylamidopropyldiethoxyethylsilane, (meth)acrylamidopropylmonoethoxydimethylsilane, (meth)acrylamidopropylmonoethoxy-diethylsilane, (meth)acrylamidobutyl-trimethoxy-silane,(meth)acrylamidobutyldimethoxy-methylsilane,(meth)acrylamidobutyldimethoxyethylsilane,(meth)acrylamidobutyl-monomethoxydimethylsilane,(meth)acrylamidobutylmonomethoxydiethylsilane,(meth)acrylamidobutyltriethoxysilane,(meth)acrylamidobutyldiethoxymethylsilane,(meth)acrylamidobutyl-diethoxyethylsilane,(meth)acrylamidobutylmonoethoxy-dimethylsilane,(meth)acrylamidobutylmonoethoxydiethylsilane,(meth)acrylamidoalkyl-amimosilanes such as(meth)acrylamidodimethylaminosilane, and(meth)acryl-amidodiethylaminosilane, (meth)acrylamidoalkylhalogensilanessuch as (meth)acryl-amidodimethylchlorosilane,(meth)acrylamidodiethylchlorosilane,(meth)acryl-amidodimpropylchlorosilane,(meth)acryl-amidomethyidichlorosilane(meth)acrylamidoethyl-dichlorosilane, and(meth)acrylamido-propyidichlorosilane.

[0019] Examples of preferred (meth)acrylamide-based monomers m₂ arefunctionalised, or non-functionalised, C₁-C₃₀alkylbutyl(meth)acrylamides such as propyl(meth)acrylamide,isopropyl(meth)acrylamide, butyl(meth)acrylamide,tert-butyl(meth)acrylamide, pentyl(meth)acrylamide,hexyl(meth)acrylamide, heptyl(meth)acrylamide, octyl(meth)-acrylamide,nonyl(meth)acrylamide, decyl(meth)acrylamide, and,octadecyl(meth)-acrylamide.

[0020] Examples of preferred monomers m₃ are bis-acrylamides such asN,N′-ethylenebis-acrylamide, N,N′-propylenebis-acrylamide, and,N,N′-butylenebis-acrylamide.

[0021] The monomers, m₁, m₂ and m₃, are suitably selected so that arandom distribution of monomers in the polymer is achieved.

[0022] The polymer suitably comprises from about 1 to about 100 mole %of units of monomer m₁, preferably from about 10 to about 90 mole %,most preferably from about 30 to about 70 mole %. Also, the polymersuitably comprises from 0 to about 99 mole % of units of monomer m₂,preferably from about 10 to about 90 mole %, most preferably from about30 to about 70 mole %. Furthermore, the polymer suitably comprises from0 to about 99 mole % of units of monomer m₃, preferably from 0 to about50 mole %.

[0023] The weight average molecular weight of the polymer is suitablyfrom about 1000 to about 500000 g/mole, preferably from about 1500 toabout 100000 g/mole, most preferably from about 2000 to about 25000g/mole.

[0024] The number of monomer units per polymer chain is suitably fromabout 5 to about 2000, preferably from about 8 to about 500, mostpreferably from about 10 to about 100.

[0025] The polymer is suitably prepared by polymerising the monomers inan organic solvent in the presence of an initiator, and optionally achain-transfer agent such as a mercapto compound. The solvent may be anyorganic solvent suitable as polymerisation medium and includes xylene,toluene, dioxane, tetrahydrofurane, chlorinated hydrocarbons, benzene,dimethylformamide, and N-methylpyrrolidone. Examples of suitableinitiators include peroxides and azo-compounds.

[0026] The polymer of the present invention is suitably covalentlybonded to the support material.

[0027] In a preferred embodiment of the present invention, a preformedpolymer, which is a copolymer of an acrylamide monomer comprising silaneand alkoxy groups and a further acrylamide monomer is covalently bondedto the surface of a silica particle.

[0028] The polymer is suitably reacted with the support material bypreparing a mixture from a suspension of the support material in asolvent with a solution of the polymer. The solvent used to suspend thesupport material is suitably an organic solvent. Suitably, the amountsupport material added to the solvent is from about 0.01 to about 1 gsupport material /ml solvent, preferably from about 0.05 to about 0.5g/ml. The amount polymer, added to the support material is a measurementof the degree of surface coverage of the support material. The amountpolymer added to the support material, calculated as monomers within thepolymer, is suitably from about 0.5 to about 20 μmole of monomer per m2support material surface, preferably from about 1 to about 15 μmole ofmonomer per m2 support material surface, even more preferably from about4 to about 12 μmole of monomer per m2 support material surface, mostpreferably from about 6 to about 10 μmole of monomer per m² supportmaterial surface. If the support material comprises pores, the amountpolymer added to the support material may also be dependent on the poresize of the support material. For diffusion pores with pore sizes from20 up to 150 Å, the amount polymer added to the support material,calculated as monomers within the polymer, is preferably from about 3 toabout 10 μmole of monomer per m² support material surface. For diffusionpores with pore sizes from above 150 up to 250 Å, the amount polymeradded to the support material, calculated as monomers within thepolymer, is preferably from about 5 to about 12 μmole of monomer per m²support material surface. For diffusion pores with pore sizes from above250 up to 500 Å, the amount polymer added to the support material,calculated as monomers within the polymer, is preferably from about 7 toabout 15 μmole of monomer per m² support material surface.

[0029] The temperature during the reaction is suitably from about 10 toabout 200° C., preferably from about 50 to about 160° C. Suitably, themixture is kept under inert atmosphere.

[0030] The invention will now further be described in connection withthe following examples which, however, not should be interpreted aslimiting the scope of the invention.

EXAMPLES Example 1

[0031]8.5 g N-(tri-methoxypropylsilyl) acrylamide and 13.4 g n-octylacrylamide were dissolved in 65 ml xylene. This solution was added intoa reaction vessel together with a peroxide initiator dissolved in 45 mlxylene. The polymerisation was performed during 7 hours under inertatmosphere at 140° C. The resulting polymer had a weight averagemolecular weight of 7000 Dalton. The conversion of monomers was morethan 98%.

Example 2

[0032]4.0 g of silica particles of the type Kromasil® having a volumeaverage particle size of 5 μm, a pore size of 100 Å, and a specificsurface area of 330 m²/g, were suspended in 30 ml xylene. 12 ml of thepolymer solution of example 1 was added and the mixture was left for 18hours at 140° C. under inert atmosphere. The particles were thereafterfiltered off, washed and dried. The particles were analysed by elementalanalysis to comprise 13.7 % carbon and 1.53 % nitrogen, whichcorresponds to a coverage of 4.5 μmole/m², calculated as μmole/m² ofmonomers included in the polymer. The formula for calculating thesurface coverage (for nitrogen-containing polymers) is:N_(c)10⁶/[(14×100×n_(c)−(N_(c)×M−N_(c)))×S], wherein N_(c) is themeasured nitrogen weight percentage, n_(c) is the number of nitrogenatoms in the monomer of the polymer bonded to silica, M is the averagemolecular weight of the monomer(s) included in the polymer, and S is thespecific surface area of the silica.

Example 3

[0033] The same procedure as in example 2 was employed, but with usingsilica particles of the type Kromasil® having a volume average particlesize of 5 μm, a pore size of 200 Å, and a specific surface area of 213m²/g. The particles were analysed to comprise 11.3% carbon and 1.285%nitrogen, which corresponds to a surface coverage of 5.2 μmole/m².

Example 4

[0034] The same procedure as in example 2 was employed, but with usingsilica particles of the type Kromasil® having a volume average particlesize of 5 μm, a pore size of 300 Å, and a specific surface area of 77m²/g. The particles were analysed to comprise 5.75% carbon and 0.735%nitrogen, which corresponds to a surface coverage of 7.6 μmole/m².

Example 5

[0035]5.5 g N-(monomethoxy-dimethyl-propylsilyl) acrylamide and 6.2 gisopropyl acrylamide were dissolved in 100 ml xylene. This solution wasadded into a reaction vessel together with a peroxide initiatordissolved in 45 ml xylene. The polymerisation was performed during 6hours under inert atmosphere at 140° C. The resulting polymer had aweight average molecular weight of 3400 Dalton. The conversion ofmonomers was more than 98%.

Example 6

[0036]5.5 g N-(monomethoxy-dimethyl-propylsilyl) acrylamide and 7.0 gn-butyl acrylamide were dissolved in 100 ml xylene. This solution wasadded into a reaction vessel together with a peroxide initiatordissolved in 45 ml xylene. The polymerisation was performed during 6hours under inert atmosphere at 140° C. The resulting polymer had aweight average molecular weight of 2500 Dalton. The conversion ofmonomers was more than 98%.

Example 7

[0037]15 g of silica particles of the type Kromasil® having a volumeaverage particle size of 5 μm, a pore size of 100 Å, and a specificsurface area of 330 m²/g, were suspended in 150 ml polymer solution madeaccording to example 5. The mixture was left for 18 hours at 140° C.under inert atmosphere. The particles were thereafter filtered off,washed and dried. The particles were analysed by elemental analysis tocomprise 17.6% carbon and 2.7% nitrogen, which corresponds to a coverageof 7.6 μmole/m², calculated as μmole/m² of monomers included in thepolymer.

Example 8

[0038] The same procedure as in example 7 was employed, except that apolymer solution made according to example 6 was used. The particleswere analysed by elemental analysis to comprise 16.7% carbon and 2.5%nitrogen, which corresponds to a surface coverage of 7.0 μmole/m²,calculated as μmole/m² of monomers included in the polymer.

1. An adsorbent material for chromatography comprising a polymerimmobilised onto a support, wherein the polymer backbone is attached tothe support by one or more linkages which comprise one or more amidegroups.
 2. An adsorbent material according to claim 1, wherein thesupport is an inorganic oxide.
 3. An adsorbent material according toclaim 2, wherein the support is silica.
 4. An adsorbent materialaccording to claim 1, wherein the polymer is prepared by polymerising amonomer mixture comprising at least one vinyl monomer ml having groupssusceptible to reaction with the support and one or more amide groups.5. An adsorbent material according to claim 4, wherein the vinyl monomerm₁ is of the general formula (I):

wherein a is a halogen, a vinyl group, or, a silane group, whereinx=1-30, R₁ is hydrogen or C₁-C₄ alkyl, and R₂ is hydrogen or methyl. 6.An adsorbent material according to claim 5, wherein the silane group hasthe general formula (IV): (B)_(y)(D)_(3-y)Si—  (IV), wherein B is C₁-C₄alkyl, C₁-C₄ alkoxy, halogen, hydroxyl, hydrogen, —N(R₃)_(z)(R₄)_(2-z),an imidazol group, a morpholine group, or an azide group, D is C₁-C₄alkyl, y=1-3, z=1-2, R₃ and R₄ are, independently from each other,hydrogen, C₁-C₂₀ alkyl, or aryl.
 7. An adsorbent material according toclaim 4, wherein the monomer mixture further comprises at least onevinyl monomer m₂ of the general formula:

wherein R₅ is hydrogen or methyl, and E is any of the groups:

R₇—O—, wherein m=0 to 20, R₆ is hydrogen or C₁-C₄ alkyl, and R₇ is afunctional moiety selected to give the desired separationcharacteristics of the finished adsorbent material.
 8. An adsorbentmaterial according to claim 6, wherein the monomer mixture furthercomprises at least one vinyl monomer m₃ of the general formula (III):

wherein n=1 to 20, R₈ is hydrogen or methyl, R₉ is hydrogen or C₁-C₄alkyl, R₁₀ is hydrogen or C₁-C₄ alkyl, and R₁₁ is hydrogen or methyl. 9.An adsorbent material according to claim 1, wherein the weight averagemolecular weight of the polymer is from about 2000 to about 25000g/mole.
 10. An adsorbent material according to claim 1, wherein thesupport has a volume average particle size of from about 1 to about 40μm.
 11. A method of preparing an adsorbent material for chromatographycomprising immobilising a polymer onto a support, wherein the support isreacted with the polymer, thereby forming one or more linkages betweenthe polymer backbone and the support, each linkage comprises one or moreamide groups.
 12. A method according to claim 11, wherein the support isan inorganic oxide.
 13. A method according to claim 12, wherein thesupport is silica.
 14. A method according to claim 11, wherein thepolymer is prepared by polymerising a monomer mixture comprising atleast one vinyl monomer m₁ having groups susceptible to reaction withthe support and one or more amide groups.
 15. A method according toclaim 14, wherein the vinyl monomer m₁ is of the general formula (I):

wherein A is a halogen, a vinyl group, or, a silane group, whereinx=1-30, R₁ is hydrogen or C₁-C₄ alkyl, and R₂ is hydrogen or methyl. 16.A method according to claim 15, wherein the silane group has the generalformula (IV): (B)_(y)(D)_(3-y)Si—  (IV), wherein B is C₁-C₄ alkyl, C₁-C₄alkoxy, halogen, hydroxyl, hydrogen, —N(R₃)_(z)(R₄)_(2-z), an imidazolgroup, a morpholine group, or an azide group, D is C₁-C₄ alkyl, y=1-3,z=1-2, R₃ and R₄ are, independently from each other, hydrogen, C₁-C₂₀alkyl, or aryl.
 17. A method according to claim 14, wherein the monomermixture further comprises at least one vinyl monomer m₂ of the generalformula:

wherein R₅ is hydrogen or methyl, and E is any of the groups:

R₇—O—, wherein m=0 to 20, R₆ is hydrogen or C₁-C₄ alkyl, and R₇ is afunctional moiety selected to give the desired separationcharacteristics of the finished adsorbent material.
 18. A methodaccording to claim 16, wherein the monomer mixture further comprises atleast one vinyl monomer m₃ of the general formula (III):

wherein n=1 to 20, R₈ is hydrogen or methyl, R₉ is hydrogen or C₁-C₄alkyl, R₁₀ is hydrogen or C₁-C₄ alkyl, and R₁₁ is hydrogen or methyl.19. A method according to claim 11, wherein the weight average molecularweight of the polymer is from about 2000 to about 25000 g/mole.
 20. Amethod according to claim 11, wherein the support has a volume averageparticle size of from about 1 to about 40 μm.
 21. A method according toclaim 11, wherein the polymer is added as a solution to a suspension ofthe support.
 22. A method of preparing an adsorbent material forchromatography, comprising providing a polymer prepared from a monomermixture comprising an amide group containing silane, reacting thepolymer with a support to form one or more linkages between the polymerbackbone and the support.
 23. A method according to claim 22, whereinthe support is an inorganic oxide.
 24. A method according to claim 23,wherein the support is silica.
 25. A method according to claim 22,wherein the polymer is prepared by polymerising a monomer mixturecomprising at least one vinyl monomer m₁ having groups susceptible toreaction with the support and one or more amide groups.
 26. A methodaccording to claim 25, wherein the vinyl monomer m₁ is of the generalformula (I):

wherein A is a halogen, a vinyl group, or, a silane group, whereinx=1-30, R₁ is hydrogen or C₁-C₄ alkyl, and R₂ is hydrogen or methyl. 27.A method according to claim 26, wherein the silane group has the generalformula (IV): (B)_(y)(D)_(3-y)Si—  (IV), wherein B is C₁-C₄ alkyl, C₁-C₄alkoxy, halogen, hydroxyl, hydrogen, —N(R₃)_(z)(R₄)_(2-z), an imidazolgroup, a morpholine group, or an azide group, D is C₁-C₄ alkyl, y=1-3,z=1-2, R₃ and R₄ are, independently from each other, hydrogen, C₁-C₂₀alkyl, or aryl.
 28. A method according to claim 25, wherein the monomermixture further comprises at least one vinyl monomer m₂ of the generalformula:

wherein R₅ is hydrogen or methyl, and E is any of the groups:

R₇—O—, wherein m=0 to 20, R₆ is hydrogen or C₁-C₄ alkyl, and R₇ is afunctional moiety selected to give the desired separationcharacteristics of the finished adsorbent material.
 29. A methodaccording to claim 27, wherein the monomer mixture further comprises atleast one vinyl monomer m₃ of the general formula (III):

wherein n=1 to 20, R₈ is hydrogen or methyl, R₉ is hydrogen or C₁-C₄alkyl, R₁₀ is hydrogen or C₁-C₄ alkyl, and R₁₁ is hydrogen or methyl.30. A method according to claim 22, wherein the weight average molecularweight of the polymer is from about 2000 to about 25000 g/mole.
 31. Amethod according to claim 22, wherein the support has a volume averageparticle size of from about 1 to about 40 μm.
 32. A method according toclaim 22, wherein the polymer is added as a solution to a suspension ofthe support.
 33. An adsorbent material for chromatography obtained byimmobilising a polymer onto a support, wherein the support is reactedwith the polymer, thereby forming one or more linkages between thepolymer backbone and the support, each linkage comprises one or moreamide groups.
 34. A method of separating chemical compounds from amixture comprising contacting the mixture with an adsorbent material forchromatography comprising a polymer immobilised onto a support, whereinthe polymer backbone is attached to the support by one or more linkageswhich comprise one or more amide groups.